Flexible composites and applications including the flexible composites

ABSTRACT

A flexible composite includes a ply having a non-orthogonal orientation. The flexible composite may be a component of a flexible assembly. The flexible assembly may be any number of fabric-based assemblies such as a radome cover of a radome, a belt for an industrial machine, an expanision joint to connect ducts of a factory, and/or a roof or skylight of a structure (notably permanent structures). The ply may be individually stabilized by a stabilizing agent such as a matrix material. The ply may be woven and may include warp yarns and fill yarns.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) fromco-pending U.S. Provisional Patent Application Ser. No. 60/466,762,filed Apr. 30, 2003, incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Some woven materials are advantageously made by having fill yarns thatare not orthogonal to the warp yarns. For instance, material used tomake covers for radar antennas, other radar systems, and other types ofantennas. These covers may be referred to as “radome covers.” Radomecovers may be as large as 80 to 168 feet or larger in diameter and canbe mounted on a platform or foundation where they are subject to highwind speeds. In some locations, a cover must be capable of withstandingwind speeds up to 200 mph. Because of their size and the possibly highwind speeds, the covers are often exposed to high stresses in alldirections along its surface. The covers must also, in manycircumstances, be capable of withstanding the effects of harshenvironmental conditions (sun, heavy rain, ice, blowing sand,temperature extremes, high winds, etc.). To accomplish this, the covermay be constructed of multiple layers (plies) having yarns running indifferent directions. This may be accomplished by taking two plies, eachhaving an orthogonal orientation, and stitching or otherwise bonding thetwo plies together such that the warp yarns of a first ply are at a 45degree angle from the warp yarns of a second ply.

These covers are used to protect various antennas. For instance, theyare typically used to cover weather radar antennas, air surveillanceradar antennas, satellite communication station antennas, and otherantenna.

Industrial belts are another woven material based product that mayadvantageously be made by having fill yarns that are not orthogonal tothe warp yarns. These belts are often subject to high stresses due toexcess applied tension (required to prevent slippage of the conveyorbelt on the machine drive rolls), stretching, heavy loads conveyed bythe belt, and high speed movement combined with side to side movementinduced by guiding systems or off-tracking problems. Applied tension,thermal extremes and thermal shock, often cause belt distortion (e.g.longitudinal ridges). In addition, tracking problems can occur due touneven warp yarn tension.

Expansion joints are used to span the distance between rigid ductwork,connecting for example, a metal flue duct with a metal or solidemissions stack in a power plant (the various pipes, ducts, and otherconduits herein referred to as “conduits” unless stated otherwise in aclaim). The expansion joint compensates for and accommodates dimensionalchanges associated with the expansion and contraction of the ductwork,as it is exposed to thermal cycling. It acts like a bellows as the solidductwork expands and contracts as it transitions through heating andcooling cycles. The expansion joint must accommodate stresses,intermittent flexing and environmental conditions (high winds,temperature excursions, sunlight, caustic flue gasses) associated withthe application.

Many designs for these applications are limited by current technology inmaking the individual plies. Individual plies can be oriented such thatthe angle of the fill yarns with respect to the warp yarns is changed.If not purposefully stabilized, yarns that are non-orthogonal tend torevert to an orthogonal pattern. Thus, if handled, these oriented pliestend to lose their preferred orientation. Further, current methods ofholding an oriented ply in place often require that the oriented ply beheld by tacking, stitching, or bonding it to some other article. Thisrequirement limits the ability to design custom fabrics which have thebest combination of properly constructed plies for a particularapplication. Further, these techniques are awkward and difficult interms of manufacturing. It would be preferable to have a system thatallows individual plies to be manufactured, where the individual pliesare able to maintain their orientation. It would also be preferable tohave a multi-ply material where each ply contributes a uniquecontribution to the overall composition; a material where each ply canhave its own geometric configuration of the yarns, its own matrixmaterial, and its own resin content.

Under current processes used to make non-orthogonal fabrics, a processis used wherein the fabric must be handled between the time in which theorientation of the fabric is made non-orthogonal and the time at whichthe non-orthogonal orientation is set. During this time period, thefabric may tend to revert to an orthogonal orientation. It would bedesirable to have a continuous process for setting a non-orthogonalorientation of a fabric that shortens the time period in which thefabric may tend to revert to an orthogonal orientation. If a continuousprocess will not be used, it would be desirable to be able to bettermaintain the non-orthogonal orientation in the time period between whenthe orientation of the fabric is made non-orthogonal and the time whenthe non-orthogonal orientation is set.

The fabrics of many of these materials are desirably coated. Thiscoating can have the purpose of resisting environmental elements,maintaining physical properties (including strength and interplyadhesions), or of otherwise making the woven fabric more functional.When plies that have been fixed together (to hold their orientation)before coating, it is difficult to create a multi-ply material with goodwet out during the coating process. Poor wet out leads to internal voidsand surface defects (blisters, bubbles, and craters) in thecoating—possibly from air trying to escape the voids during the coatingprocess.

The teachings herein below extend to those embodiments which fall withinthe scope of the appended claims, regardless of whether they accomplishone or more of the above-mentioned needs.

SUMMARY OF THE INVENTION

One embodiment is directed to a ply of woven material in which theorientation of the fill yarns are non-orthogonal to the warp yarns. Thematerial further comprises a polymer coating, which stabilizes thenon-orthogonal orientation of the yarns.

Another embodiment is directed to a multi-ply woven material. Thematerial includes a first ply having fill yarns orthogonal to its warpyarns, and a second ply having fill yarns that are not orthogonal to itswarp yarns. At least the second ply of the material is individuallystabilized.

Another embodiment is directed to a multi-ply woven material. Thematerial includes a first ply having fill yarns and warp yarns, and asecond ply having fill yarns that are not orthogonal to its warp yarns.At least the second ply of the material is individually coated.

Another embodiment is directed to a multi-ply composite. The compositecomprises a first ply and a second ply, the second ply having anon-orthogonal orientation. The second ply is woven and is individuallystabilized.

Another embodiment is directed to a composite. The composite comprises awoven ply having a non-orthogonal orientation. The woven ply isindividually stabilized by a matrix material selected from the groupconsisting of silicone rubber, urethane rubber, polyvinyl chloride,polyvinylidene chloride, polyvinyl alcohol, fluoropolymers, urethane,polyurethane, and combinations thereof.

Another embodiment is directed to a flexible composite. The flexiblecomposite comprises a woven ply having a non-orthogonal orientation. Thewoven ply of the flexible composite is individually stabilized.

Another embodiment is directed to a multi-ply material. The multi-plymaterial includes a first woven ply, a second woven ply, and a thirdwoven ply fixedly coupled to the first and second plies. At least oneply of the multi-ply material has fill yarns that are not orthogonal toits warp yarns, and each ply has an about equal resin content.

Another embodiment is directed to a multi-ply material. The multi-plymaterial includes three plies. The middle ply is fixedly coupled to theother two plies and has a resin content at least as high as both of theouter plies. The middle ply has a non-orthogonal orientation.

Another embodiment is directed to a flexible multi-ply material. Theflexible multi-ply material comprises a first ply and a second ply. Thefirst ply and the second ply are not coupled to each other by stitching.The plies may be laminated to each other.

Another embodiment is directed to a flexible multiply composite. Theflexible multi-ply composite comprises a first ply, a second ply, and athird ply. At least one of the first ply, second ply, and third plycomprises a non-orthogonal orientation. In some embodiments, at leasttwo of the first ply, second ply, and third ply comprise non-orthogonalorientations. Each of the three plies may comprise woven plies. Theflexible multi-ply material may comprise a fourth ply.Another embodiment is directed to a structure comprised of a fabric asdisclosed in the previous paragraphs. The structure may comprise aradome comprising a flexible radome cover, a machine comprising a belt,a building comprising a flexible roof and/or a skylight, a piping systemcomprising a flexible expansion joint, and a boat comprising sails.

Another embodiment is directed to a radome. The radome includes amulti-ply material configured to cover an antenna. The multi-plymaterial comprises a first ply having fill yarns and warp yarns, and asecond ply having fill yarns that are not orthogonal to the warp yarns.At least the second ply of the multi-layer material is individuallycoated.

Another embodiment is directed to a wireless signal-based structure. Thestructure includes an antenna, and a cover. The cover includes amulti-ply material having a first ply having fill yarns and warp yarns,and a second ply having fill yarns that are not orthogonal to its warpyarns. At least the second ply of the cover is individually coated.

Another embodiment is directed to a radome cover. The radome covercomprises a woven ply, the ply comprising a first set of yarns and asecond set of yarns. The first set of yarns and second set of yarns arearranged such that the ply has a non-orthogonal orientation.

Another embodiment is directed to a radome cover. The radome covercomprises a multi-ply material comprising a first woven ply having fillyarns and warp yarns, the first ply having a negative orientation; and asecond woven ply coupled to the first ply and having fill yarns and warpyarns, the second ply having a positive orientation.

Another embodiment is directed to a radome cover. The radome covercomprises a woven ply, the ply comprising a first set of yarns and asecond set of yarns arranged such that the ply has a non-orthogonalorientation. The ply of the radome cover is individually stabilized.

Another embodiment is directed to a radome cover. The radome covercomprises a first ply and a second ply. The radome cover has atrapezoidal tear strength of at least about 300 lbs. The trapezoidaltear strength may be measured in a warp, fill, or diagonal direction.The radome cover may have a trapezoidal tear strength of at least about400 or at least about 600 lbs. The radome cover may have two or moretrapezoidal tear strengths of at least about 300 lbs (e.g. warp, fill,first diagonal, and/or second diagonal).

Another embodiment is directed to a radome cover. The radome covercomprises a first ply, a second ply, and a third ply. The radome covermay comprise a fourth ply. One of the plies of the radome may comprise anon-orthogonal orientation. Each of the plies may comprise woven plies.

Another embodiment is directed to a radome comprising a radome coverconfigured according to any of the embodiments disclosed above.

Another embodiment is directed to a system comprising an antenna and aradome, a radome cover of the radome being configured according to anyof the embodiments discussed above.

Another embodiment is directed to an industrial belt. The belt includesa multi-ply material configured to carry a load. The multi-ply materialhas a first ply having fill yarns and warp yarns, and a second plyhaving fill yarns that are not orthogonal to the warp yarns. At leastthe second ply of the multi-ply material is individually coated.Further, the multi-ply material is configured to form a loop.

Another embodiment is directed to a machine having a belt with greaterdimensional stability. The machine includes a belt comprising amulti-ply material. The multi-ply material includes a first ply havingfill yarns and warp yarns, and a second ply, the second ply having fillyarns that are not orthogonal to the warp yarns. The second ply isindividually stabilized. The machine further includes a drivingmechanism coupled to the belt such that the driving mechanism causes thebelt to move.

Another embodiment is directed to a composite to be formed into a belt.The fabric comprises a woven ply, the ply comprising a first set ofyarns and a second set of yarns. The first set of yarns and second setof yarns are arranged in a non-orthogonal orientation.

Another embodiment is directed to a composite to be formed into a belt.The composite comprises a woven ply, the ply comprising a first set ofyarns and a second set of yarns arranged such that the ply has anon-orthogonal orientation. The ply of the belt is individuallystabilized.

Another embodiment is directed to a composite to be formed as a belt.The composite comprises a multi-ply material comprising a first wovenply having fill yarns and warp yarns, the first ply having a negativeorientation; and a second woven ply coupled to the first ply and havingfill yarns and warp yarns, the second ply having a positive orientation.

Another embodiment is directed to a belt formed from a compositeconstructed according to any of the embodiments discussed above. Thebelt may comprise an open weave belt.

Another embodiment is directed to a machine comprising rollers andhaving a belt constructed according to any of the embodiments discussedabove stretched between the rollers.

Another embodiment is directed to a machine comprising a drivingmechanism and having a belt constructed according to any of theembodiments discussed above coupled to the driving mechanism such thatthe driving mechanism can be operated to cause the belt to move.

Another embodiment is directed to a method of using a belt according toany of the embodiments discussed above. The method comprises carryingpackages weighing more than 60 pounds using the belt.

Another embodiment is directed to a method of using a belt according toany of the embodiments discussed above. The method comprises dryingarticles using the belt.

Another embodiment is directed to an architectural fabric. Thearchitectural fabric comprises a first woven ply; and a second wovenply. The first woven ply and the second woven ply of the architecturalfabric are integrally coupled.

Another embodiment is directed to an architectural fabric. Thearchitectural fabric comprises a woven ply, the ply comprising a firstset of yarns and a second set of yarns. The first set of yarns and thesecond set of yarns are arranged such that the ply has a non-orthogonalorientation.

Another embodiment is directed to an architectural fabric. Thearchitectural fabric comprises a woven ply, the ply comprising a firstset of yarns and a second set of yarns arranged in a non-orthogonalorientation. The ply of the architectural fabric is individuallystabilized.

Another embodiment is directed to a roof comprising an architecturalfabric constructed according to any of the embodiments discussed above.

Another embodiment is directed to a structure comprising anarchitectural fabric constructed according to any of the embodimentsdiscussed above.

Another embodiment is directed to a structure including a roof, the roofcomprising an architectural fabric constructed according to any of theembodiments discussed above.

Another embodiment is directed to a fabric expansion joint. Theexpansion joint comprises a woven ply, the ply comprising a first set ofyarns and a second set of yarns. The first set of yarns and second setof yarns are arranged in a non-orthogonal orientation.

Another embodiment is directed to a fabric expansion joint. Theexpansion joint comprises a ply, the ply comprising a first set of yarnsand a second set of yarns arranged in a non-orthogonal orientation. Theply of the expansion joint is individually stabilized.

Another embodiment is directed to an assembly. The assembly comprises afirst conduit, a second conduit, and an expansion joint extendingbetween the first conduit and the second conduit. The expansion jointmay be constructed according to any of the embodiments discussed above.The first and second conduits may be rigid and may have a fixedposition.

Another embodiment is directed to a system for forming an individuallystabilized ply. The system comprises an accumulator configured toreceive a woven fabric ply; and a means for individually stabilizing anon-orthogonal orientation of the woven fabric ply after it has beenaccumulated by the accumulator. The ply may be individually stabilizedby coating, laminating, or by some other method. An orientation of theply may be changed by one of an accumulator and a payout station (whichmay include changing the orientation using both an accumulator and apayout station).

Another embodiment is directed to a system for forming an individuallystabilized ply. The system comprises a means for altering an orientationof a woven fabric ply; and a means for individually stabilizing thealtered orientation of the woven fabric ply.

Another embodiment is directed to a method of forming a woven material.The method includes inputting a material having warp yarns and fillyarns, changing the angle of the fill yarns with respect to the warpyarns, such that the warp yarns and fill yarns are non-orthogonal, andcoating the material at about the time.

Another embodiment is directed to a method. The method comprises coatinga material having yarns at an angle to each other, and changing theangle of the yarns with respect to each other in the coated material.

Another embodiment is directed to a method for forming a woven material.The method comprises forming a single ply of material having yarns at anangle with respect to each other, changing an angle of the yarns withrespect to each other at a time, and coating the single ply of materialat about the same time.

Another embodiment is directed to a method for forming an individuallystabilized ply. The method includes weaving a ply having a firstorientation; changing the orientation of the ply that has been woven;and individually stabilizing the changed orientation of the ply.

Another embodiment is directed to a method for stabilizing a ply. Themethod comprises forming a ply having a non-orthogonal orientation; andcoating the ply in its non-orthogonal orientation to individuallystabilize the ply.

Another embodiment is directed to a method for stabilizing a ply. Themethod comprises forming a ply having a non-orthogonal orientation; andlaminating the ply in its non-orthogonal orientation to individuallystabilize the ply.

Another embodiment is directed to a method for forming an individuallystabilized ply. The method comprises weaving a ply; maintaining thewoven ply in a non-orthogonal orientation for an extended period beforethe ply is individually stabilized; and individually stabilizing the plythat has been maintained in its non-orthogonal orientation.

A number of methods and products are directed to woven materials. Thesemethods could also be used to form more knitted materials (and otherfabrics). Further, even though some embodiments are directed to coatingof the fabrics, these fabrics could also be laminated, or go throughsome other process for applying a stabilizing compound.

Other principle features, advantages, and variations falling within thescope of the invention will become apparent to those skilled in the artupon review of the following drawings, the detailed description, and theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams showing woven materials with warp and fillyarns at orthogonal and non-orthogonal angles;

FIG. 2 is a layer diagram illustrating a multi-layered material havinglayers which can be individually coated;

FIG. 3A is a flow diagram of a method for forming flexible compositeshaving at least one ply with a non-orthogonal orientation;

FIG. 3B is a flow diagram for a method for forming single layermaterials which can maintain a non-orthognal warp yarn—fill yarnrelationship (orientation) without being fixed to another layer prior tostabilization of the orientation;

FIG. 3C is a flow diagram for a method for forming multi-layer materialsfrom various preformed plies;

FIG. 3D is a flow diagram of a method for forming a radome from amulti-layer material having at least one ply having a non-orthogonalorientation;

FIG. 3E is a flow diagram of a method of using a belt comprising atleast one ply having a non-orthogonal orientation;

FIGS. 4A to 4C are one illustration of a system that can be used tocarry out the method described in FIG. 3B;

FIG. 5A is an antenna based system according to one embodiment;

FIG. 5B is a radome according to one embodiment;

FIG. 5C is a layer diagram of a multi-layer material for use as a radomeaccording to one embodiment;

FIG. 6A is a machine having a fabric based belt according to oneembodiment;

FIG. 6B is a layer diagram of a multi-layer material for use as anindustrial belt according to one embodiment;

FIG. 7A is a cross-sectional side view of a structure having a roof madeof a multi-layer material according to one embodiment;

FIG. 7B is a plan view of the structure shown in FIG. 7A;

FIG. 7C is a layer diagram of a multi-layer material for use as astructural material according to one embodiment; and

FIG. 8A is an industrial system incorporating an expansion jointaccording to one embodiment; and

FIG. 8B is a layer diagram of a multi-layer material that may be used toform an expansion joint according to one embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1A and 1B, an orthogonal ply of woven material 6includes fill yarns 12 that are orthogonal to warp yarns 10. Anon-orthogonal ply of woven material 8, on the other hand, has fillyarns 12 that are not orthogonal to warp yarns 10. Non-orthogonal pliescan be characterized by the skew angle (α) between warp yarns 10 andfill yarns 12 and the direction in which fill yarns 12 run (from left toright). Skew angle (α) is defined by the smallest angle (0°<α<90° forplies with a non-orthogonal orientation) between warp yarns 10 and fillyarns 12. Material 8 is at about a 45° angle and has fill yarns thatrise. A material 8 that has fill yarns that rise is typically referredto as having a positive skew angle, having an Z orientation, and/orhaving a right-hand orientation.

The fact that fill yarns 12 rise is typically inconsequential since asingle ply of material 8 is generally symmetrical, and, when coated asan individual ply, can be flipped over to have fill yarns 12 that fall.In a multi-layer material, orientation may be determined with respect tosome reference. For instance, in a radome, orientation is determinedwith reference to an observer who is on the inside of the radome. Thesame may be true when using the multi-layer material in an architecturaland/or expansion joint application.

Reference to orientation of a ply is a reference of the orientation of afirst set of yarns of the ply (e.g. fill yarns) with respect to a secondset of yarns that are non-parallel to the first set (e.g. warp yarns).Unless stated otherwise, “orientation” of a ply is generally a referenceto the skew angle of the yarns of the ply.

Reference to a shape/geometry of a ply or a multi-layer material shallmean the three-dimensional form of the ply and/or the material.

Skew angle shall be a reference to the angle formed between one set ofyarns (e.g. warp yarns) and a second set of yarns (e.g. fill yarns) ifthe ply were placed as a flat (generally two-dimensional) sheet. Sets ofyarns that are parallel would have a 0 degree skew angle and sets ofyarns that are orthogonal would have a 90 degree skew angle. In a wovenmaterial, skew angle generally refers to the angle formed by the warpyarns and fill yarns.

A matrix material is generally a different material than thefibers/yarns which it holds in place. While matrix materials arediscussed herein with respect to some embodiments, any place that theterm matrix material is used in the description of the figures, thedescription could alternately use the terms stabilizing agent or bondingagent.

Fabric as used herein shall refer to a textile structure produced byinterlacing yarns, fibers, or filaments. Fabric tends to initially besubstantially planar, but the fabric may tend to curl, or otherwisedeform from a planar shape due to the orientation of the layer(s) usedto make the fabric. A fabric with a non-planar shape is contemplated bythis application.

A fabric according to this application tends to be formed by weavingand/or knitting. Fabric having woven and/or knitted plies shall bereferred to as an intertwined fabric or an intertwined ply. Weaving asused herein is not limited to joining two yarns made of similarmaterials.

A coated fabric as used herein shall refer to any fabric to which asubstance such as a lacquer, plastic, resin, rubber, or varnish has beenapplied in firmly adhering layers to provide certain properties, such asstabilization of the orientation of the fabric.

Reference to a non-orthogonal orientation of a ply is a reference to anon-orthogonal orientation of at least a whole section of the ply, andnot merely a reference to the orientation of the ply at certain points(such as at the fringes of the ply). Further, reference to anon-orthogonal orientation is generally a reference to a ply having askew of of more than about 5 and less than about 85. These limits areset to differentiate between manufacturing deviations that occur inorthogonal plies, and plies that actually have a non-orthogonalorientation as the term is meant to be used herein.

Referring to FIG. 2, a multi-layer material 100 has a first orthogonallayer 102 (alpha ≈90°), a first non-orthogonal layer 104 (alpha ≈45°), asecond non-orthogonal layer 106 (alpha ≈30°), a second orthogonal layer108 (alpha ≈90°), and a third non-orthogonal layer 110 (alpha ≈45°).While not common in a large number of embodiments, it is conceivablethat a single ply may have multiple orientations. In most embodiments, asingle ply will have substantially the same orientation throughout theply (i.e. there may be minor deviations in the orientation—for instance,at the fringes of the ply—but the ply general has a constant orientationthroughout the ply).

The individual layers can be individually designed and individuallycoated. When the layers are individually coated, each layer can have itsown yarn material and matrix material, and its own yarn geometry andresin content. Further, layer 110 may have its non-orthogonal yarnorientation maintained by individually coating layer 110, while layers104 and 106 (or some other layers) have their non-orthogonal yarnorientation maintained by use of stitching.

Multi-layer material 100 may be designed to be a flexible composite.Examples of applications that may employ flexible composites includeradome covers (especially air-supported radome covers), belts, roofing,skylights, and other architectural fabrics, and fabric-based expansionjoints.

Multi-layer material 100 may comprise at least three plies. In otherembodiments, multi-layer material 100 may comprise at least four plies.These plies may be woven plies. One or more of these plies may have anon-orthogonal orientation, which orientation may be individuallystabilized for that ply.

Layers 102 to 110 can be held together by any number of means. Forinstance, they can be powder bonded, laminated, stitched, etc. Also,even if the individual layers are coated, multi-layer material 100 canhave an additional coating applied after any combination of layers 102to 110 have been combined.

Multiple advantages can be achieved by forming multi-layer materialsfrom individually coated/stabilized plies. For instance, non-orthogonalplies made by conventional methods are not coated until after two ormore plies have been stitched or otherwise bonded together. When thesematerials are coated, the resulting material tends to have largernumbers of surface defects and void spaces. Multi-layer materials madeby individually coating a single ply, on the other hand, tend to havefewer void spaces and fewer surface defects.

Also, multi-layer materials made by individually coating single pliescan lead to unique arrangements. For instance, a middle layer can have ahigher resin content (amount of resin per square yard) than its twoadjacent layers. Also, different resin types can be used for adjoininglayers.

Individual plies according to some embodiments may have a skew anglethat is no less than about 30 degrees or 40 degrees. Individual pliesaccording to some embodiments may have a skew angle that is no more thanabout 60 degrees or 50 degrees. These embodiments may be in any shape,including, but not limited to, radome covers, belts, architecturalfabrics, and expansion joints.

According to some embodiments of a multi-ply material, the multi-plymaterial will comprise a first ply having a positive orientation and asecond ply having a negative orientation. According to most of theseembodiments, the two opposing orientations occur in overlapping sectionsof the two plies. Again, these embodiments may be in any shape,including, but not limited to, radome covers, belts, architecturalfabrics, and expansion joints. According to some embodiments, one ormore of the plies will have a substantially closed (non-porous)structure. Further, the composite as a whole may have a substantiallyclosed structure. The substantially closed structure may be a result ofa tight weave of the yarns. According to other embodiments, thecomposite may have an open structure such as an open weave structure.

Referring to FIG. 3A, a method for creating a multi-layer fabric for aparticular application includes creating a stabilized ply of material atblock 230, using the stabilized ply (typically in conjunction with otherplies) to form a multi-layer fabric suitable for the application atblock 240, and then applying the material to the application at block250.

Referring to FIG. 3B, a method for forming a stabilized ply at block 230may include forming the material at block 200. The material could beformed by any number of conventional weaving or knitting procedures. Thematerial could also be formed by any other procedure that can create amaterial with one set of yarns at an angle to another set of yarns. Someyarns that may be used to form the plies include fiberglass, nylon,polyester, aramid (such as KEVLAR® or NOMEX® available from Dupont),polyethylene, polyolefins, polyimides, carbon, polybenzimidazole (PBI),polybenzoxazole (PBO), and/or fluorocarbon. Further, other materials maybe used to form the yarns of a ply. A yarn may be formed from one ofthese materials or may comprise a combination of these materials(potentially twisted together).

In a ply having warp yarns and fill yarns, the warp yarns and the fillyarns may have different compositions than each other. Further, the warpyarns may be a uniform composition (i.e. all warp yarns are made ofabout the same materials) or may have a non-uniform composition (i.e.some warp yarns have a different composition than other warp yarns).Further still, the fill yarns may have a uniform composition or may havea non-uniform composition.

An optional matrix material can be applied to the formed material atblock 202 prior to changing the angle of the yarns. The matrix materialcould be any number of materials applied in any number of manners. Forexample, the matrix material could be a silicone rubber, urethanerubber, a urethane, a polyurethane, polyvinyl chloride, polyvinylidenechloride, polyvinyl alcohol, and their copolymers with acrylic acid oracrylic acid esters or other vinyl ester monomers, fluoropolymers,including fluoroplastics (such as PTFE, FEP, TFA, ETFE, THV, etc.) andfluoroelastomers, some other polymeric material, or blends thereof.Typical fluoropolymer matrix materials may include monomers ofchlorotrifluoroethylene (CTFE) and vinylidene fluoride (VF2), either ashomopolymers, or as copolymers with TFE, HFP, PPVE, PMVE and ethylene orpropylene. Additionally, the fluropolymer matrix material could comprisea perfluoropolymer such as homopolymers and copolymers oftetrafluoroethylene (TFE), hexafluoropropylene (HFP) and fluorovinylethers, including perfluoropropyl and perfluoromethyl vinyl ether. Othermaterials may also be used as the matrix material. The applied materialcould alternatively be some other type of stabilizing agent.

The matrix material could be applied by coating the formed material,laminating the formed material, powder bonding the formed material,being sprayed onto the formed material, etc.

The matrix material is preferably impregnated into the yarns withminimal encapsulation; the goal being to add some stability to the shapeof the formed material, while at the same time allowing a change in theshape of the material to be carried out.

After block 202, the angle of the fill yarns with respect to the warpyarns is changed at block 204. Since most materials are formed in theirorthogonal state, changing the angle typically involves making thematerial become non-orthogonal. Also, changing the angle typicallyinvolves changing the angle throughout the material. For instance, asection of the material (a section being defined by one point along thewarp yarns to another point along the warp yarns) where all of the fillyarns are substantially orthogonal to the warp yarns would change to asection where all of the fill yarns are substantially non-orthogonal tothe warp yarns (while ideally all of the yarns would face the exact samedirection, there will inevitably be some minor deviations from thedesired angle on occasion, especially near the edges).

Additionally, changing the angle at block 204 may be carried out in morethan one step. For instance, a 45° angle may be too severe an angle toform in one step, so the 45° angle can be formed first as a 30° angleand then the 30° angle is converted to a 45° angle.

Once the angle has been set at block 204, the single ply material isthen stabilized at block 206. This process typically occurs at or aboutthe same time as the angle is formed (e.g. within about a minute or lessdepending on the speed with which the material is moved through theproduction line). This typically reduces the amount of deviation fromthe desired angle, because the non-orthogonal yarns would have less of achance to revert to an orthogonal pattern.

Alternately, a technique may be used to maintain the changed orientationof the fabric. The fabric may then be transported from the device usedto change the orientation and coated at a later point in time. One suchtechnique for maintaining a non-orthogonal orientation of an individualply is an interleaf technique. If used, the technique used to maintainthe non-orthogonal orientation of the ply can preferably be able tomaintain the orientation for extended periods of time (e.g. more thanone day).

The material used as a stabilizer at block 206 can be the same as, orcan be different from, that used as the optional impregnating materialadded at block 202. The same list of materials discussed above withrespect to block 202 may be used at block 206. The stabilizing at block206 preferably more firmly sets the angle of the material, although,while it can be held firmly and rigidly in place, the orientation of theply need not be locked in place or made entirely rigid. Material thathas been stabilized at block 206 can preferably hold its shape, in itsindividual layer form, for extended periods of time.

Here, a material is considered “stabilized” even if no physical fixingto another substance has taken place, so long as a substance (thestabilizing agent) introduced to the formed material greatly increasesthe resistance of a non-orthogonal material to deviate from itspreferred, non-orthogonal orientation.

A ply which has such a stable orientation that it will not tend toeasily revert to some other orientation may be considered stabilized. Aply which achieves this stabilization before being joined withadditional plies may be considered individually stabilized. Anindividual ply which achieves this individual stabilization by theintroduction of a matrix material may be referred to as a ply that isindividually stabilized by a matrix material.

This individual stabilization is a particularly useful property for anon-orthogonally orientated ply to have, although not all embodiments ofnon-orthogonally oriented plies according to the claimed subject matterneed be individually stabilized. Reference to a non-orthogonal ply in aclaim does not imply that the ply is individually stabilized unlessexpressly stated in the claim.

Referring to FIG. 3C, a method for forming the material at block 240 mayinclude combining the individual plies which have been stabilized inplace at block 230 to form a multi-layer material at block 208. Themulti-layer material can further be formed using uncoated layers,multi-layer materials not having individually coated layers, non-fabriclayers (such as protective coatings), etc.

Additional matrix material may be applied to the multi-layer material atblock 210. Also, other coatings and laminations can be added to themulti-layer material to affect the properties of the material.

The material is then shaped at block 212. Some typical shapes for thematerial depend on the use of the multi-layer material. For instance,when used as radomes, the material is typically formed into pieces thatcan be combined to form a truncated sphere. When used as an industrialbelt, the material is typically left in a rectangular shape, which thenis connected at its ends. Also, other substances, such as inductiveelements can be added to the material.

Once the multi-layer material is in its formed shape at block 212,further coatings and laminations can be applied to the multi-layermaterial to hold the orientation, and/or to give it other desiredproperties.

Referring to FIG. 3D, in one embodiment an article having anindividually stabilized ply with a non-orthogonal orientation may beapplied at block 250 to an air-supported radome. In a radome having sucha stabilized ply, a base ring may be set around the base of the antennaat block 214. The base ring may have a plurality of clamps and may beprepared with an adhesive secured gasket and/or anti-seizing spray.

The radome fabric is then placed over the antenna at block 216. Theradome fabric may be lifted over the antenna using a crane. Depending onthe construction of the radome, this step may be better accomplished ifwind speeds are not high.

The radome fabric is then connected to the base ring at block 218 thismay be done by way of the clamps on the base ring. Once this isaccomplished, an air-supported radome may be inflated (e.g. usingblowers).

Referring to FIG. 3E, a belt comprising an individually stabilized plymay be attached to an apparatus at block 220. An article may then beplaced on the belt at block 222. The article may be a heavy article andmay have a weight of at least about 40 or 60 pounds. If the apparatus atblock 220 is part of a system for drying articles, the belt may be usedto dry the article at block 224. Using a belt to dry or cure an articlemay include using the belt to convey the article through a zone ofincreased temperature often in conjunction with a cooling zone. The beltis thus subject to both thermal extremes and thermal cycling.

Referring to FIG. 4A, an embodiment of an apparatus for forming plies ofmaterial with a non-orthogonal orientation includes a payout station 320which pays out fabric to an accumulator 330. Fabric from accumulator 330passes through dip pan 340 where fabric 306 is coated with matrixmaterial. Fabric from dip pan 340 passes between metering bars 346 andgoes through tower 350. Tower 350 may be used to dry, bake, sinter,and/or cure the matrix material onto the fabric. After passing throughtower 350, the fabric is taken up by take-up 360.

Payout station 320 may be used to skew fabric 306. Referring to FIG. 4B,payout station 320 includes a roll 322 carrying material with a startingorientation. The material is fed from roll 322 to capstan rollers 324.Roll 322 may be set at an angle 326 from rollers 324. When angle 326 isnon-zero, the tension between roll 322 and rollers 324 may cause fabric306 to change its orientation. Angle 326 is generally placed betweenzero and forty-five degrees.

Accumulator 330 may also be used to skew fabric 306. Referring to FIG.4C, accumulator 330 includes upper accumulator rolls 334 and loweraccumulator rolls 332. If upper rolls 334 and lower rolls 332 are placedat a non-zero angle 336 with respect to each other, then tension betweenrolls 334 and rolls 332 may cause fabric 306 to change its orientation.Here, upper rolls 334 are shown as the rolls which are adjusted toadjust angle 336. In other embodiments, lower rolls 332 are adjusted orboth upper rolls 334 and lower rolls 332 are adjusted. This process maybe repeated within the accumulator for each of the sets of rollers.Angle 336 may be set to be between zero and fifteen degrees, or may beset equal to zero or fifteen degrees.

In some embodiments payout station 320 is used to change the orientationof fabric 306. In other embodiments, accumulator 330 is used to changethe orientation of fabric 306. In either of these embodiments, acombination of payout station 320 and accumulator 330 may be used tochange the orientation of fabric 306.

Capstans 324, 342, and 362 may be used to adjust the amount of tensionprovided to fabric 306. Also, the distance between metering bars 346 maybe used to control the thickness of an applied coating. Further, theshape of metering bars 346 may be used to control the surface texture offabric 306. For instance, a metering bar 346 may include notches to formribs on fabric 306, and may move from side to side to form the ribs in anon-linear pattern.

Instead of using a dip coating apparatus, some other coating apparatusmay be used to coat fabric 306.

Radomes

Referring to FIGS. 5A and 5B, an assembly 400 includes an antenna 402supported on a tower 404. Antenna 402 is covered by radome 406 which isalso supported on tower 404. Antenna 402 could alternately be located ona building, could be ground-based, etc.

Radome 406 is configured to protect antenna 402 from the elementswithout causing significant interference to the signals to betransmitted and received by antenna 402. Radome 406 may be configured tohave good performance at high frequencies and/or good performance atmultiple frequencies. Radome 406 would preferably have low transmissive,absorptive, and/or reflective loss of signal at high/multiplefrequencies. A lack of significant interference may indicate that theradome cover contributes to a signal loss of no more than about 0.5% ofthe signal strength from the signal source at at least one andpotentially at multiple frequencies. Good performance may indicate thatthe radome cover contributes to a signal loss of no more than about0.05% at one or more frequencies.

Antenna 402 may be a high frequency radar antenna. Antenna 402 could bea phased array or a dish (such as a parabolic dish, a split cylinderdish) and may be rotating or non-rotating. Radomes 406 are used as partof a number of different types of radar system assemblies. For example,radomes 406 can be used in conjunction with weather radar systems, andairport radar systems.

Instead of using a radar antenna, assembly 400 could include otherantennas 402, one such antenna being a satellite communication antenna.One example of an assembly 400 using a satellite communication antennais a ground terminal for the US Air Force unmanned aircraft.

Radome 406 primarily includes a multi-layer material 430. Multi-layermaterial 430 is typically between about 0.04 and 0.1 inch thick,although other thickness are possible. In some embodiments, multi-layermaterial 430 may be less than 0.04 inches or may be as thick as 0.3inches. In one embodiment, multi-layer material 430 is about 0.07 to0.09 inches thick.

In some embodiments, multi-layer material 430 may have a warptrapezoidal tear strength of at least about 300 lbs, or may be selectedto have a warp trapezoidal tear strength of at least about 450 lbs. Inanother embodiment, multi-layer material 430 may be selected to have awarp trapezoidal tear strength of at least about 650 lbs.

In some embodiments, multi-layer material 430 may have a filltrapezoidal tear strength of at least about 300 lbs, or may be selectedto have a fill trapezoidal tear strength of at least about 450 lbs. Inanother embodiment, multi-layer material 430 may be selected to have afill trapezoidal tear strength of at least about 650 lbs.

In some embodiments, multi-layer material 430 may have a trapezoidaltear strength at a first diagonal of at least about 300 lbs, or may beselected to have a diagonal trapezoidal tear strength of at least about450 lbs. In another embodiment, multi-layer material 430 may be selectedto have a diagonal trapezoidal tear strength of at least about 650 lbs.In some of these embodiments, multi-layer material 430 may have atrapezoidal tear strength at a second diagonal of at least about 300lbs, or may be selected to have a second diagonal trapezoidal tearstrength of at least about 450 lbs. In another of these embodiments,multi-layer material 430 may be selected to have a second diagonaltrapezoidal tear strength of at least about 650 lbs.

In some embodiments, multi-layer material 430 may have a weight of atleast about 65 osy or may be selected to have a weight of at least about75 osy. In some embodiments, multi-layer 430 material may be selected tohave a weight of less than about 100 osy or may be selected to have aweight less than about 90 osy.

In some embodiments, multi-layer material 430 may have a warp striptensile strength of at least about 1300 lbs./in. or may be selected tohave a warp strip tensile strength of at least about 1600 lbs./in. Inone embodiment, multi-layer material 430 may be selected to have a warpstrip tensile strength of no more than about 1900 lbs./in.

In some embodiments, multi-layer material 430 may have a fill striptensile strength of at least about 1300 lbs./in. or may be selected tohave a fill strip tensile strength of at least about 1600 lbs./in. Inone embodiment, multi-layer material 430 may be selected to have a fillstrip tensile strength of no more than about 1900 lbs./in.

In some embodiments, multi-layer material 430 may have a warp tensilestrength after a 50 pound creasefold of at least about 1200 lbs./in. ormay be selected to have a warp tensile strength after a 50 poundcreasefold of at least about 1650 lbs./in. In some embodiments,multi-layer material 430 may have a warp tensile strength after a 50pound creasefold of no more than about 2000 lbs./in., or may be selectedto have a warp tensile strength after a 50 pound creasefold of no morethan about 1900 lbs./in.

In some embodiments, multi-layer material 430 may have a fill tensilestrength after a 50 pound creasefold of at least about 1200 lbs./in. ormay be selected to have a fill tensile strength after a 50 poundcreasefold of at least about 1650 lbs./in. In some embodiments,multi-layer material 430 may have a fill tensile strength after a 50pound creasefold of no more than about 2000 lbs./in., or may be selectedto have a fill tensile strength after a 50 pound creasefold of no morethan about 1900 lbs./in.

According to one embodiment, a foam layer 432 may be added tomulti-layer material 430. Foam layer 432 primarily serves as a layer ofinsulation for antenna 402. Foam layer 432 may also serve to providestructural support to radome 406. As illustrated in FIG. 5B, radome 406may also include structural support elements 434 integrally connectingportions of radome 406, which are used as supports for the structure ofradome 406.

While not limited to such radomes, the fabrics described in the presentapplication may have a greater contribution to radome covers that relyon multi-layer material 430 to provide the primary structural supportfor the radome cover. These radomes may be radomes that do not includefoam layer 432 and/or secondary structural support elements 434.

One example of a radome in which multi-layer fabric 430 may serve as aprimary structural member responsible for bearing loads is anair-supported radome. An air-supported radome may rely on a differencein air-pressure (e.g. a higher air pressure inside the radome) tosupport the radome instead of relying solely on structural supportelements 434. Typical air-supported radomes 406 may be configured to notinclude secondary structural support elements 434 at all. Anair-supported radome 406 may also lack foam layer 432.

An air-supported radome may include a blower pressurization systemconfigured to maintain the increased air pressure. In one embodiment,the blower pressurization system comprises a three-stage blowerpressurization system. The blower pressurization system may include ablower such as a 230/460 VAC, 3 phase, 60 Hz power blower, may includeone or more anemometers, an external pressure tap, and an air intakeassembly. An air-supported radome 406 may also include a galvanizedsteel base ring assembly, and a lifting ring. Radome 406 may alsoinclude airlock door assemblies, a lightning rod assembly, andcirculation fans.

Some objectives for selecting characteristics of a multi-ply materialused to form a radome include providing high tensile strength inmultiple directions (such as three or four directions), retainingtensile strength in the multiple directions after handling and flexing,balanced elongation/modulus in the multiple directions, inter-plyintegrity, flexibility, ability to pattern, fabricate, and cut thematerial, and the ability to both be RF transmissive with a low loss ofsignal strength and/or accuracy and not sustain negative side effectsfrom RF transmission—such as overheating—(e.g. choosing materials withlow amounts of interaction with the signal(s) at their intendedfrequency or frequencies).

A primary consideration for meeting the objectives is the selection ofan appropriate yarn material. The properties of the material from whichthe yarns are made can have a significant affect on the tensile strengthof the radome, the retained tensile strength of the material, theflexibility of the radome, resistance to environmental elements, balanceof modulus and elongation, and other of the objectives listed above. Forinstance synthetic fibers, especially an aramid such as KEVLAR, mayprovide sufficient flexibility and retention of tensile strength for usein radome applications. Matrix materials can also be selected forspecific characteristics. Typically, fluoroploymers are selected towithstand temperature requirements, provide sufficient RF transmissivityand to provide protection from the elements (rain, sun, etc).

Also, the use of orthogonal and non-orthogonal plies should be a primarydesign consideration. When non-orthogonal plies are used, the size anddirection of the oriented yarns may affect how the loads are shared. Aproper choice of orientation, angle and direction, could result in amore even distribution of load sharing between yarns, and may result inmore even load sharing in multiple directions. Further, non-orthogonallayers may be combined having one layer with a positive angle andanother layer with a negative angle to achieve better results. Also, theselection of the orientation of individual plies of the multi-plymaterial may affect the overall tensile strength of the radome in thevarious directions.

Other considerations that may affect these properties include theprocessing history (such as thermal cycling), use of twisted yarns,crimp balance, and choice of which yarns will bear structural loads.

Yarns bearing structural loads will typically be thicker than yarns thatare not intended to bear structural loads. Reference to a non-structuralyarn does not mean that when placed in the field the yarn will not besubjected to and bear some loads, but rather, that it is not intended tobe a primary bearer of the load.

Structural yarns may be placed in even increments around the fabric(i.e. the structural yarns may be located every certain angleamount—such as every 30 degrees, every 45 degrees, every 60 degrees,etc.). Alternatively, the structural yarns may be placed in unevenincrements around the fabric (i.e. not at regularly spaced intervals).

The number of directions in which structural yarns extend in amulti-layer material may be used to differentiate the multi-layermaterial. For instance, a material having structural yarns in twodirections may be referred to as bi-axial, three directions istri-axial, etc. An orthogonal ply with structural warp and fill yarnswould be considered to be bi-axial. A multi-layer material having twoorthogonal plies where the warp yarns of one ply are rotated 45 degreesfrom the warp yarns of the other ply, and where the warp and fill yarnsof each ply contain structural yarns would be considered to be aquadri-axial material. Radome covers and flexible composites accordingto some embodiments would comprise multi-axial materials.

Referring to FIG. 5C, one exemplary embodiment of a multi-layer material430 which may be useful in a radome application comprises a plurality ofplies 462–466 which are coupled to each other. Plies 462–466 may bejoined by stitching the plies together, laminating the plies together,powder bonding the plies together, and/or may be joined by some othermethod. The plies may be directly connected, or they may be indirectlyconnected by intervening materials.

Multi-layer material 460 may include a protective film 461 on a surface468 of multi-layer material 460 which is facing the environment.Multi-layer material 460 may also have a protective film (not shown)located on an interior face 470. Further still, multi-layer material 460may only have a film on interior face 470.

Protective film 461 may be designed to block UV light and may bedesigned to protect plies 462–466 from the penetration of environmentalelements (such as water, sand/dirt, and others).

One or more of plies 462–466 may be individually stabilized and/or havea non-orthogonal orientation. Further, one of plies 462–466 may have anegative orientation and another may have a positive orientation.

Also, additional plies may be added to multi-layer material 460 orillustrated plies may be removed from multi-layer material 460. In someembodiments, multi-layer material 460 may be composed essentially ofabout two to about six plies.

Plies 426–466 may comprise yarns of any of the materials described withrespect to block 200 (FIG. 3B). Typical yarns used to form radomesinclude aramids (such as KEVLAR), fiberglass, and/or polyester. Theplies 462–466 may have warp yarns made of one material and fill yarnsmade of another material. Further, the yarns may comprise more than onetype of material. Further still, each of plies 462–466 may have its ownunique set of yarns.

Exemplary matrix materials for plies 462–466 include any of the matrixmaterials described above with respect to block 202 (FIG. 3B). A typicalmatrix material used to form a radome includes PTFE.

Multi-layer material 460 may be a flexible composite of the individualplies and matrix materials.

Other properties and characteristics of plies used in the constructionof multi-layer materials used as radome covers can be determined withreference to FIGS. 1 to 4C above. Methods of forming radome covers maybe seen with respect to FIGS. 3A to 3D above.

Belts

Referring to FIGS. 6A and 6B, an industrial machine 500 has a belt 502and a driving mechanism 504. The driving mechanism 504 includes rollers506, 508 which are coupled to motor 510. Belt 502 is stretched acrossrollers 506, 508 and may be placed under tension. If tension is appliedto belt 502, the tension may result in deformation of the belt.

The belt may also tend to be deformed by the use of automatic trackingsystems used to keep the belt aligned on the equipment. Further still,the belt may tend to be deformed by an uneven placement of loads on thebelt.

These forces may be applied at angles that are not parallel orperpendicular to the direction of travel of the belt, and may not beadequately compensated for by the use of orthogonal plies with yarnsrunning in a direction parallel to the intended direction of travel ofthe belt.

Multi-layer material 530 of belt 502 is preferably configured to resistshape deformation due to the tension, thermal cycling, thermal extremesand side to side stress to which it is subjected, and thereby retainbetter dimensional stability.

To compensate for these forces, the belt fabric may include plies withyarns which are non-perpendicular and non-parallel to the longitudinaldirection of the belt. One example of such a ply would be anon-orthogonal ply with warp yarns that are perpendicular to thedirection of travel of the belt (e.g. having fill yarns that arenon-perpendicular and non-parallel to the longitudinal direction of thebelt). A non-orthagonal construction may tend to more uniformitydistribute and deflect loads, thereby mitigating or preventing sometracking problems.

Dimensional stability can be increased by specifically designing beltsto resist deformation. One manner of doing this is designing a belt withlayers having warp and fill yarns at different angles. The layers mayalso be made having different coatings. Using individually coated layersallows greater ability to design a belt with optimal properties,including increased dimensional stability.

Dimensional stability may be an issue for belts having an open weavesince the warp yarns and fill yarns are not as densely packed. Such openweave belts are commonly classified as controlled porosity belts or openmesh belts. Controlled porosity belts tend to have a total amount ofopen area of greater than 0% and less than about 15%, and haveporosities of about 5 to 50 SCFM. The current design may be more usefulwhen directed to controlled porosity belts having a more open design,such as about 5% to about 15% open area. Open mesh belts, on the otherhand, tend to have a total amount of open area greater than 10%,typically having an open area in the range of 10% to about 80%. In someembodiments, such open mesh belts will have a total amount of open areathat is no less than about 30%. Also, in some embodiments, such openmesh belts will have a total amount of open area that is no more thanabout 60%.

Open weave designs including only orthogonal plies may tend to deform(narrow, ridge, and/or fold over) when pulled at certain angles or whenexposed to thermal cycling. The addition of skewed plies adds strengthat angles where orthogonal plies do not add strength, thereby improvingthe dimensional stability of the belt at those angles.

In one embodiment, the multi-layer material of the present applicationis not a closed porosity belt (e.g. does not have a total open area ofabout 0%).

Belt 502 may comprise a multi-layer material 520. Such a multi-layermaterial 520 may include plies that have warp yarns which arenon-orthogonal to fill yarns. Use of such skewed plies may cause belt502 to curl, ridge, or fold over. To counter the tendency to curl,ridge, or fold over, one or more orthogonal plies may be included inbelt 502, preferably as the outer layers.

Open weave belts with improved dimensional stability may be useful inapplications such as drying applications.

When designing a belt, it is advantageous to choose plies withproperties which contribute to the dimensional stability, flex fatigueresistance, inter-ply adhesion, tear strength, tracking, beltelongation, thermal cycling, and use temperature of the belt. Theorientation of the plies of the fabric of the belt primarily contributesto the dimensional stability of the belt.

Referring to FIG. 6B, one exemplary embodiment of a multi-layer material520 which may be useful in a belt application comprises a plurality ofplies 522–528 which are coupled to each other. Plies 522–528 may bejoined by stitching the plies together, laminating the plies together,powder bonding the plies together, or may be joined by some othermethod. The plies may be directly connected, or they may be indirectlyconnected together by intervening materials.

One or more of plies 522–528 may be individually stabilized and/or havea non-orthogonal orientation. Further, one of plies 522–528 may have anegative orientation and another may have a positive orientation.

Multi-layer material 520 may include a protective film (not shown) on aface 550 of multi-layer material 520. Multi-layer material 520 may alsohave a protective film (not shown) located on a face 552 of multi-layermaterial 520 opposite from face 550. Further still, multi-layer material520 may only have a film on face 552.

Also, additional plies may be added to multi-layer material 520 orillustrated plies may be removed from multi-layer material 520. In someembodiments, multi-layer material 520 may be composed essentially ofabout three to about six plies.

Additionally, multi-layer material 520 may include flights (not shown)integral with multi-layer material 520. Flights may include ribs,cleats, ridges, lugs, or other protuberances. The flights may be locatedon either or both of surfaces 550 and 552. The flights may be continuousor discontinuous. The flights may be located transverse to the directionof travel of the belt (e.g. to prevent items from slipping) or mayextend parallel to the direction of the belt (e.g. to prevent the beltfrom weaving from side to side). If flights are on both faces ofmulti-layer material 520, the flights may extend in the same direction(such as for use in contact toasters) or may extend in differentdirections (e.g. parallel flights on the bottom face of the belt toprevent weaving and transverse flights on the top of the belt to preventslippage).

Plies 522–528 may comprise yarns of any of the materials described withrespect to block 200 (FIG. 3B). The type of yarn that is commonly usedfor a particular belt depends on the application for which the belt isbeing used. For example, a belt designed to be used in a hightemperature application may include yarns comprising fiberglass, anaramid such as KEVLAR or NOMEX®, some other high temperature yarn, oryarns comprised of combinations of these materials. As another example,open mesh belts used in drying applications commonly include yarnscomprised of fiberglass/NOMEX®, Glass/KEVLAR®, NOMEX®/KEVLAR® orcombinations thereof. The plies 522–528 may have warp yarns made of onematerial and fill yarns made of another material. Further, the yarns maybe comprised of combinations of materials. Further still, each of plies522–528 may have its own unique set of yarns.

Exemplary matrix materials for plies 522–528 include any of the matrixmaterials described above with respect to block 202 (FIG. 3B). Again,the type of matrix material that is commonly used for a particular beltdepends on the application for which the belt is being used. Forexample, a belt designed to be used in a high temperature applicationwhere a low coefficient of friction is needed may use a matrix materialcomprising a fluoropolymer such as PTFE or some other material meetingthese standards. As another example, open mesh belts used in dryingapplications commonly include matrix materials comprising siliconerubber and/or PTFE. A belt for use in a high temperature cookingapplication may comprise a silicone rubber matrix material.

Multi-layer material 520 may be a flexible composite of the individualplies and matrix materials.

Other properties and characteristics of plies used in the constructionof multi-layer materials used as belts can be determined with referenceto FIGS. 1 to 4C above. One method of using a belt according to oneembodiment may be seen with respect to FIG. 3E above.

Architectural Fabrics

Referring to FIGS. 7A–7C, a structure 600 includes walls 601, 602 androof 604. Roof 604 includes support beams 606 and a multi-layer material608 which is supported by support beams 606. Alternatively, roof 604could include some type of support mechanism other than support beams606 such as cabling and/or air pressure. Multi-layer material 608 ispreferably designed to allow light to shine through, but not allow otherenvironmental elements, such as dust and water, to pass through. Someexamples of structures 600 that use a high performance fabric as a roofmaterial include sports stadiums (such as the Minneapolis Metrodome) andairports (such as Denver International Airport). Forming the roofmaterial from individually coated layers allows greater flexibility whendesigning a roof with optimal properties.

Multi-layer material 608 is preferably designed to be at least partiallylight transmissive. The term “translucent” will be used to refer to thelight transmissivity and will refer to both translucent and transparentmaterials unless stated otherwise in a claim at issue. Some embodimentsof multi-layer material 608 have an overall light transmissivity of atleast about at 5. Some of these embodiments have an overall lighttransmissivity of at least about 20%. Some embodiments have an overalllight transmissivity of no more than about 5%. Some of these embodimentshave an overall light transmissivty of no more than about 45%.

One material which may be suitable for allowing light transmission isglass fibers and polyester/nylon. These materials may be coated withpolytetrafluroethylene (PTFE), poly vinyl chloride (PVC) and/or liquidsilicone rubber (LSR) or some other form of silicone rubber.

Architectural fabrics may be classified between permanent structures andmovable structures. While usable for both types of structures,multi-layer material 608 formed as disclosed in this application tendsto be more applicable to permanent structures. More particularly, suchmulti-layer materials may be useful for forming roofs or skylights forpermanent structures like domes and airports.

Referring to FIG. 7C, one exemplary embodiment of a multi-layer material640 which may be useful in an architectural application (especially fora permanent structure) comprises a plurality of plies 644–648 which arecoupled to each other. Plies 644–648 may be joined by stitching theplies together, laminating the plies together, powder bonding the pliestogether, or may be joined by some other method. The plies may bedirectly connected, or they may be indirectly connected together byintervening materials.

One or more of plies 644–648 may be individually stabilized and/or havea non-orthogonal orientation. Further, one of plies 644–648 may have anegative orientation and another may have a positive orientation.

Multi-layer material 640 may include a protective film 642 on anexternal face 660 of multi-layer material 640 facing the environment.Multi-layer material 640 may also have a protective film (not shown)located on a face 662 of multi-layer material 640 exposed to theinterior of the structure. Multi-layer material 640 generally does nothave a protective layer on interior face 662 without also having aprotective layer on external face 660 in products intended for use asroofing and skylight materials.

The protective layer 642 is generally chosen to be translucent and maybe clear, tinted, or some combination of clear and tinted. A suitabletint for a protective layer 642 of a material 640 configured to be usedas a roofing or skylight material is a blue tint. Protective layer 642may be used to make multi-layer material 640 waterproof and may be usedto protect the yarns of the plies 644–648 from environmental elements.Protective layer 642 may include pigments which may impart color forarchitectural decorative effect.

Protective layer 644 may include a fluoropolymer which may protect thecomposite from rain, aid in shedding snow more easily, and/or provide aself-cleaning surface.

Also, additional plies may be added to multi-layer material 640 orillustrated plies may be removed from multi-layer material 640. In someembodiments, multi-layer material 640 may be composed essentially ofabout two to about five plies.

Plies 644–648 may comprise yarns of any of the materials described withrespect to block 200 (FIG. 3B). The type of yarn that is commonly usedfor architectural fabrics depends on the application in which the fabricis being used. For example, when the fabric is used as a roofing orskylight material of a structure (and particularly for permanentstructures), common yarn materials include polyester, nylon, KEVLAR,and/or fiberglass. The plies 644–648 may have warp yarns made of onematerial and fill yarns made of another material. Further, the yarns maybe comprised of combinations of these materials. Further still, each ofplies 644–648 may have its own unique set of yarns.

Exemplary matrix materials for plies 644–648 include any of the matrixmaterials described above with respect to block 202 (FIG. 3B). The typeof matrix material that is commonly used for architectural fabricsdepends on the application in which the fabric is being used. Forexample, when the fabric is used as a roofing or skylight material of astructure (and particularly for permanent structures), common matrixmaterials include PTFE, PVC, and silicone rubber.

Multi-layer material 640 may be a flexible composite of the individualplies and matrix materials.

Other properties and characteristics of plies used in the constructionof multi-layer materials for use as architectural fabrics can bedetermined with reference to FIGS. 1 to 4C above. Methods of formingarchitectural fabrics may be seen with respect to FIG. 3A above.

Expansion Joints

Referring to FIG. 8A, an industrial system 700 includes a first rigidconduit 710 coupled to a second rigid conduit 712 by an expansion joint714. Expansion joint 714 is connected to first conduit 710 by firstconnectors 718 (which may comprise bolts) and to second conduit 712 bysecond connectors 719. Industrial system 700 may also include bars 716extending between first conduit 710 and second conduit 712. Expansionjoint 714 may be comprised of a multi-layer material 730 (FIG. 8B).

Extending between may mean that the extending item extends from oneconduit to the other, may mean that a portion of the item extends in thelength between the two conduits, may mean that the entire extending itemis located in a space between the conduits (whether directly connectedor not), or may include other positions consistent with the ordinarymeaning of the term.

Expansion joint 714 may have a bellow-like shape. Expansion joint 714may be used to span the gap between two gas stream containments (e.g.smoke stack and power generation plant). Alternately, expansion joint714 may be used to fabricate chutes in a chemical plants. Expansionjoint 714 could also be used for other purposes.

When designing expansion joints, it is advantageous to design amulti-layer material 730 with plies that contribute to the tensilestrength, tear strength, flex fatigue resistance, inter-ply adhesion,and use temperature of the expansion joint. The orientation of the pliesmay contribute to the ability to uniformly distribute loads as well asprevent tear migration by deflecting the direction of the stress.

Referring to FIG. 8B, one exemplary embodiment of a multi-layer material730 which may be useful in an expansion joint application comprises aplurality of layers 740–746 which are coupled to each other. Plies740–744 may be joined by stitching the plies together, laminating theplies together, powder bonding the plies together, and/or may be joinedby some other method. The plies may be directly connected, or they maybe indirectly connected together by intervening materials.

Multi-layer material 730 may include a protective film 746 on a surface734 of multi-layer material 730 which is facing an interior of theexpansion joint 716. Protective film 746 may be configured to protectthe remainder of multi-layer material 730 from the articles beingtransported through conduits 710, 712 (FIG. 8A). For instance, thematerial in the ducts of a powerplant may include fine particles (“ash”)as well as hot corrosives. Film 746 may include polytetrafluoroethylene(PTFE), or other fluropolymers films including but not limited toperfluoroalkoxy (PFA) and fluorinated ethylene-propylene (FEP). Also, insome embodiments film 746 may be selected to have a thickness that is atleast about 0.002 inches and/or may be selected to have a thickness thatis no more than about 0.1 inches.

One or more of plies 740–744 may be individually stabilized and have anon-orthogonal orientation. Further, one or more of plies 740–744 mayhave a negative orientation and one or more may have a positiveorientation.

Also, additional plies may be added to multi-layer material 730 orillustrated plies may be removed from multi-layer material 730. In someembodiments, multi-layer material 730 may be composed essentially ofabout two to about five plies.

Plies 740–744 may comprise yarns of any of the materials described withrespect to block 200 (FIG. 3B). Typical yarns used to form expansionjoints include fiberglass, NOMEX®& KEVLAR®. The plies 740–744 may havewarp yarns made of one material and fill yarns made of another material.Further, each of plies 740–744 may have its own unique set of yarns. Theyarns may also be hybrid; consisting of one yarn plied of severaldifferent fibers (e.g. glass, NOMEX®, KEVLAR®) in one or bothdirections.

Exemplary matrix materials for plies 740–744 include any of the matrixmaterials described above with respect to block 202 (FIG. 3B). Typicalmatrix materials used to form expansion joints include PTFE, FEP & PFAalong with a fluroelastomer.

Multi-layer material 730 may be a flexible composite of the individualplies and matrix materials.

Other properties and characteristics of plies used in the constructionof mult-layer materials used as expansion joints can be determined withreference to FIGS. 1 to 4C above.

EXAMPLES

The following example is presented to illustrate the present inventionand to assist one of ordinary skill in making and using the same. Theexamples are not intended in any way to otherwise limit the scope of theinvention.

Example 1

Layer Warp Yarn Fill Yarn Matrix Structural Number Material MaterialMaterial Orientation Yarns 1 Kevlar Kevlar PTFE Orthogonal Warp, Fill 2Kevlar Kevlar PTFE −60° Fill 3 Kevlar Kevlar PTFE +60° Fill

According to this exemplary embodiment, which may be useful for aradome, a multi-layer material 460 (FIG. 5C) includes a first ply 462with an orthogonal orientation, a second ply 464 with a negativeorientation, and a third ply 466 with a positive orientation. First ply462, second ply 464, and third ply 466 comprise KEVLAR warp and fillyarns woven together and coated with PTFE. Second ply 464 and third ply466 have 60 degree skew angles, and have fill yarns that are structuraland warp yarns that are non-structural. When formed as multi-layermaterial 430, the warp yarns of first ply 462, second ply 464, and thirdply 466 extend in about the same (parallel) direction. Plies 462–466 arelaminated together using technology such as that disclosed in U.S. Pat.No. 5,141,800. Alternatively, plies 462–466 may be stitched togetherusing threads.

Multi-layer material 430 has a first face 468 extending towards theoutside environment and a second face 470 facing the interior of radome406. The two skew plies 464, 466 are located towards interior face 470and the orthogonal ply 462 is located towards exterior face 468.

A protective layer 461 is applied to first ply 462 as a barrier betweenthe plies and the environment. Protective layer 461 may include a UVblocking film which includes PTFE, TiO2, and carbon black. One such UVblocking film is sold by Saint-Gobain Performance Plastics under thename CHEMFILM™.

Example 2

Layer Warp Yarn Fill Yarn Matrix Structural Number Material MaterialMaterial Orientation Yarns 1 Kevlar Kevlar PTFE Orthogonal Warp, Fill 2Kevlar Kevlar PTFE −45° Fill 3 Kevlar Kevlar PTFE +45° Fill

According to this exemplary embodiment, which may be useful for aradome, a multi-layer material 460 (FIG. 5C) includes a first ply 462with an orthogonal orientation, a second ply 464 with a negativeorientation, and a third ply 466 with a positive orientation. First ply462, second ply 464, and third ply 466 comprise KEVLAR warp and fillyarns woven together and coated with PTFE. Second ply 464 and third ply466 have 45 degree skew angles, and have fill yarns that are structuraland warp yarns that are non-structural. When formed as multi-layermaterial 430, the warp yarns of first ply 462, second ply 464, and thirdply 466 extend in about the same direction. Plies 462–466 are laminatedtogether using technology such as that disclosed in U.S. Pat. No.5,141,800. Alternatively, plies 462–466 may be stitched together usingthreads.

Multi-layer material 430 has a first face 468 extending towards theoutside environment and a second face 470 facing the interior of radome406. The two skew plies 464, 466 are located towards interior face 470and the orthogonal ply 462 is located towards exterior face 468.

A protective layer 461 is applied to first ply 462 as a barrier betweenthe plies and the environment. Protective layer 461 includes a UVblocking film which may include PTFE, TiO2, and carbon black. One suchUV blocking film is sold by Saint-Gobain Performance Plastics under thename CHEMFILM™.

Example 3

Layer Warp Yarn Fill Yarn Matrix Structural Number Material MaterialMaterial Orientation Yarns 1 Kevlar Kevlar PTFE Orthogonal Warp, Fill 2Kevlar Kevlar PTFE −30° Fill 3 Kevlar Kevlar PTFE +60° Fill 4 KevlarKevlar PTFE −60° Fill 5 Kevlar Kevlar PTFE +30° Fill

According to this exemplary embodiment, which may be useful for aradome, a multi-layer material 460 (FIG. 5C) includes a first ply 462with an orthogonal orientation, a second ply 464 and a fourth ply (notshown) with negative orientations, and a third ply 466 and a fifth ply(not shown) with positive orientations. First ply 462, second ply 464,third ply 466, the fourth ply, and the fifth ply comprise KEVLAR warpand fill yarns woven together and coated with PTFE. Third ply 466 andthe fourth ply have 60 degree skew angles, and have fill yarns that arestructural and warp yarns that are non-structural. Second ply 464 andthe fifth ply have 30 degree skew angles, and have fill yarns that arestructural and warp yarns that are non-structural. When formed asmulti-layer material 430, the warp yarns of first ply 462, second ply464, third ply 466, the fourth ply and the fifth ply extend in about thesame direction. The five plies are laminated together using technologysuch as that disclosed in U.S. Pat. No. 5,141,800. Alternatively, theplies may be stitched together using threads.

Multi-layer material 430 has a first face 468 extending towards theoutside environment and a second face 470 facing the interior of radome406. The two skew plies 464, 466 are located towards interior face 470and the orthogonal ply 462 is located towards exterior face 468.

A protective layer 461 is applied to first ply 462 as a barrier betweenthe plies and the environment. Protective layer 461 includes a UVblocking film which may include PTFE, TiO2, and carbon black. One suchUV blocking film is sold by Saint-Gobain Performance Plastics under thename CHEMFILM™.

Example 4

Layer Warp Yarn Fill Yarn Matrix Structural Number Material MaterialMaterial Orientation Yarns 1 Kevlar Kevlar PTFE −60° Fill, Warp 2 KevlarKevlar PTFE +60° Fill, Warp

According to this exemplary embodiment, which may be useful for aradome, a multi-layer material 460 (FIG. 5C) includes a first ply 462with a negative orientation, and a second ply 464 with a positiveorientation. First ply 462 and second ply 464 comprise KEVLAR warp andfill yarns woven together and coated with PTFE. First ply 462 and secondply 464 have 60 degree skew angles, and have fill yarns that arestructural. Plies 462 and 464 also have warp yarns which each bear about50% of a structural load. When formed as multi-layer material 430, thewarp yarns of first ply 462 and second ply 464 extend in about the samedirection. Plies 462, 464 are laminated together using technology suchas that disclosed in U.S. Pat. No. 5,141,800. Alternatively, plies 462,464 may be stitched together using threads.

A protective layer 461 is applied to first ply 462 as a barrier betweenthe plies and the environment. Protective layer 461 includes a UVblocking film which may include PTFE, TiO2, and carbon black. One suchUV blocking film is sold by Saint-Gobain Performance Plastics under thename CHEMFILM™.

Example 5

Layer Warp Yarn Fill Yarn Matrix Structural Number Material MaterialMaterial Orientation Yarns 1 Kevlar Kevlar PTFE −45° Fill, Warp 2 KevlarKevlar PTFE +45° Fill, Warp

According to this exemplary embodiment, which may be useful for aradome, a multi-layer material 460 (FIG. 5C) includes a first ply 462with a negative orientation, and a second ply 464 with a positiveorientation. First ply 462 and second ply 464 comprise KEVLAR warp andfill yarns woven together and coated with PTFE. First ply 462 and secondply 464 have 45 degree skew angles, and have fill yarns that arestructural. Plies 462 and 464 also have warp yarns which are structuraland each bear about 50% of a structural load along a common axis. Whenformed as multi-layer material 430, the warp yarns of first ply 462 andsecond ply 464 extend in about the same direction. Plies 462, 464 arelaminated together using technology such as that disclosed in U.S. Pat.No. 5,141,800. Alternatively, plies 462, 464 may be stitched togetherusing threads.

A protective layer 461 is applied to first ply 462 as a barrier betweenthe plies and the environment. Protective layer 461 includes a UVblocking film which may include PTFE, TiO2, and carbon black. One suchUV blocking film is sold by Saint-Gobain Performance Plastics under thename CHEMFILM™.

Example 6

Layer Warp Yarn Fill Yarn Matrix Number Material Material MaterialOrientation Porosity 1 Fiberglass Fiberglass PTFE Orthogonal Open Mesh 2Fiberglass Fiberglass PTFE +45° Open Mesh 3 Fiberglass Fiberglass PTFE−45° Open Mesh 4 Fiberglass Fiberglass PTFE Orthogonal Open Mesh

According to this exemplary embodiment, which may be useful for a belt,a multi-layer material 520 (FIG. 6B) includes a first ply 522 with anorthogonal orientation, a second ply 524 with a positive orientation, athird ply 526 with a negative orientation, and a fourth ply with anorthogonal orientation. First ply 522, second ply 524, third ply 526,and fourth ply 528 comprise fiberglass warp and fill yarns woventogether and coated with PTFE. Second ply 524 and third ply 526 have 45degree skew angles. When formed as multi-layer material 520, the warpyarns of first ply 522, second ply 524, third ply 526, and fourth ply528 extend in about the same direction. Plies 522–528 are stitchedtogether using polyester or KEVLAR threads.

Multi-layer material 520 has a first face 550 facing in a firstdirection and a second face 552 facing in a second direction.Multi-layer material 520 is substantially planar. First face 550 isconfigured to carry articles on the belt and second face 552 isconfigured to face opposite the articles. The two skew plies 524, 526are located in the middle of the multi-layer fabric and the orthogonalplies 522, 528 are located towards the faces 550, 552 of the belt.

Example 7

Layer Warp Yarn Fill Yarn Matrix Number Material Material MaterialOrientation 1 Fiberglass Fiberglass Silicone +45° Rubber 2 FiberglassFiberglass Silicone −45° Rubber 3 Fiberglass Fiberglass SiliconeOrthogonal Rubber

According to this exemplary embodiment, which may be useful for anarchitectural roof fabric, a multi-layer material 640 (FIG. 7C) includesa first ply 644 with a positive orientation, a second ply 646 with anegative orientation, and a third ply 648 with an orthogonalorientation. First ply 644, second ply 646, and third ply 648 comprisefiberglass warp and fill yarns woven together and coated with siliconerubber. First ply 644 and second ply 646 have 45 degree skew angles.When formed as multi-layer material 640, the warp yarns of first ply644, second ply 646, and third ply 648 extend in about the samedirection. Plies 644–648 are stitched together using polyester threads.

Multi-layer material 640 has a first face 660 extending towards theoutside environment and a second face 662 facing the interior of thebuilding for which the roof fabric 640 is being used. The two skew plies644, 646 are located towards exterior face 660 and the orthogonal ply648 is located towards interior face 662.

A protective layer 642 is applied to first ply 644 as a barrier betweenthe plies and the environment. Protective layer 642 includes afluoropolymer.

Example 8

Layer Warp Yarn Fill Yarn Matrix Number Material Material MaterialOrientation 1 Fiberglass Fiberglass PTFE/FE Orthogonal blend 2Fiberglass Fiberglass PTFE/FE +45° blend 3 Fiberglass Fiberglass PTFE/FE−45° blend

According to this exemplary embodiment, which may be useful for anexpansion joint, a multi-layer material 730 (FIG. 8B) includes a firstply 740 with an orthogonal orientation, a second ply 742 with a positiveorientation, and a third ply 744 with a negative orientation. First ply740, second ply 742, and third ply 744 fiberglass warp and fill yarnswoven together and coated so that the Fluoroelastomer in the blendremains uncured. Second ply 742 and third ply 744 have orientations of45 degrees. When formed as multi-layer material 730, the warp yarns offirst ply 740, second ply 742, and third ply 744 extend in about thesame direction. Plies 740–744 are joined together by stitching.

Multi-layer material 730 has a first face 732 extending towards theoutside environment and a second face 734 facing the interior of thecylindrical or box-shaped expansion joint 716 (FIG. 8A). The two skewplies 742, 744 are located towards interior face 734 and the orthogonalply 740 is located towards exterior face 732.

A protective layer 746 is applied to third ply 746 as a barrier betweenthe plies and the material to be transported through expansion joint716. Protective layer 746 includes PTFE.

Example 9

Property Units Value Weight oz./sq. yd. 80 ± 3 Thickness inches 0.080nominal Strip Tensile Strength lbs./in. Warp (Dry) 1800 min average Fill(Dry) 1800 min average D 1 (Dry) 1800 min average D 2 (Dry) 1800 minaverage Strip Tensile Strength lbs./in. After 50 lbs Creasefold Warp(Dry) 1750 min average Fill (Dry) 1750 min average D 1 (Dry) 1750 minaverage D 2 (Dry) 1750 min average Tear Strength lbs. (Trapezoidal) Warp 700 min average Fill  700 min average Seam Peel Adhesion lbs./in. Dry 20 min average Wet  20 min average Uniaxial Elongation % (at 40lbs./in.) Warp 2.5 max average Fill 2.0 to 5.5 average DielectricConstant 2.35 nominal Loss Tangent 0.006 nominal Water Absorption % Lessthan 2 Hydrophobic Contact degrees 90 + nominal Angle Incombustibilityseconds 0 to flameout Service Temperature degrees F. −60 to 500

A radome cover made of a fabric which uses plies having non-orthogonallyoriented plies according to one example has the above-listed physicaland performance properties. The fabric is a multi-ply fabric where theplies are comprised of PTFE coated KEVLAR and a film is located on theouter surface of the fabric. The radome is designed to be RFtransmissive with good performance at multiple frequencies.

The exemplary fabric's quadriaxial, multi-ply, laminated constructionprovides good dimensional stability, even in the most extremeenvironments. The composite offers durable hydrophobicity, enhancedflexural characteristics, very high tear strength, and good hightemperature/fire performance.

Example 10

Property Units Value Weight oz./sq. yd. 70 ± 3 Thickness inches 0.070nominal Strip Tensile Strength lbs./in. Warp (Dry) 1200 min average Fill(Dry) 1200 min average D 1 (Dry) 1200 min average D 2 (Dry) 1200 minaverage Strip Tensile Strength lbs./in. After 50 lbs Creasefold Warp(Dry) 1150 min average Fill (Dry) 1150 min average D 1 (Dry) 1150 minaverage D 2 (Dry) 1150 min average Tear Strength lbs. (Trapezoidal) Warp 500 min average Fill  500 min average Seam Peel Adhesion lbs./in. Dry 20 min average Wet  20 min average Uniaxial Elongation % (at 40lbs./in.) Warp 2.5 max average Fill 2.5 to 5.5 average DielectricConstant 2.35 nominal Loss Tangent 0.005 nominal Water Absorption % Lessthan 2 Hydrophobic Contact degrees 90 + nominal Angle Incombustibilityseconds 0 to flameout Service Temperature degrees F −60 to 500

A radome cover made of a fabric which uses plies having non-orthogonallyoriented plies according to one example has the above-listed physicaland performance properties. The fabric is a multi-ply fabric where theplies are comprised of PTFE coated KEVLAR and a film is located on theouter surface of the fabric. The radome is designed to be RFtransmissive with good performance at multiple frequencies.

The exemplary fabric's quadriaxial, multi-ply, laminated constructionprovides good dimensional stability, even in the most extremeenvironments. The composite offers durable hydrophobicity, enhancedflexural characteristics, very high tear strength, and good hightemperature/fire performance.

Example 11

A woven fabric with a count of 8×12, warp yarns of 1000d KEVLAR and fillyarns of 3000 denier KEVLAR, is dipped at 4 fpm through a Silicone/PTFEformulation at 1.32 sg (43.4% solids). It is then dried and baked for 90seconds at 300 F and 515 F respectively.

The yarns of this woven material are subsequently reoriented onequipment depicted in FIG. 4. The payout of this equipment is angled at45 degrees to the web path. All of the other rolls are at 90 degrees tothe web path. Reorientation is done at 3 fpm without adding new coating.

Example 12

A woven fabric with a count of 8×12, warp yarns of 1000d KEVLAR and fillyarns of 3000 denier KEVLAR, is dipped at 4 fpm through a Silicone/PTFEformulation at 1.32 sg (43.4% solids). It is then dried and baked for 90seconds at 300 F and 515 F respectively.

The yarns of this woven material are subsequently reoriented onequipment depicted in FIG. 4. The payout is angled at 45 degrees to theweb path. All of the other rolls are at 90 degrees to the web path.Reorientation is done at 3 fpm. While the reorientation is occurring,the fabric is dipped through a PTFE dispersion at 1.50 sg (59.5%solids). It is then dried and baked for 120 seconds at 220 F and 630 Frespectively.

The fabric is given a third coating. 1.50 sg PTFE dispersion (59.5%) isapplied at 3 fpm, then dried and baked for 120 seconds at 220 F and 630F respectively.

Example 13

This ply consists of a 26×26 count basket weave using 2000 denier KEVLARyarn in both warp and fill. It is coated with a silicone/PTFEformulation at 1.32 sg, 4 fpm, drying and baking for 90 seconds at 300 Fand 515 F respectively.

Example 14

The coated fabrics described in examples 11 and 12 are stitched to thefabric described in example 13. These three plies are arranged in anorder of example 13, then example 12, and then example 11 and arestitched together using KEVLAR 46 Natural stitching thread (SyntheticFibers) at 4.5 gauge chain stitch with 4.5 to 7.7 stitches per inch.

The stitched composite is further coated with 42 osy of PTFE. Each PTFEcoating pass is dried and baked (2 minutes at 250 F and 555 Frespectively). The coated fabric is then sintered for 80 seconds at 750F and then coated with 15 osy of a PTFE/TiO2 formulation and finishedwith a 2 osy topcoat of FEP dispersion. Each of these passes is dried,baked and sintered for 120 seconds.

The properties of this product are:

Breaking strength Warp 1317 pli Fill 1091 pli Diagonal 1 1093 pliDiagonal 2  759 pli Trap. Tear Warp  766 lbs Fill  946 lbs Diagonal 1 733 lbs Diagonal 2  811 lbs Crease Fold Warp 1270 pli Fill 1142 pliDiagonal 1  984 pli Diagonal 2  774 pli Seam Strength Warp 1147 pli Fill1107 pli Diagonal 1  915 pli Diagonal 2  673 pli

Example 15

A woven KEVLAR fabric with a count of 10×17.5 ypi with 1140 DenierKEVLAR 49 yarn is reoriented on equipment shown in FIG. 4. Theaccumulator rolls are angled 15 degrees from the cross machine direction(75 degrees from the web path). At about the same time it is coated witha PTFE/PFA formulation containing 5% by weight PFA based on solids. Itis dried and sintered for 90 seconds at 300 F and 680 F respectively.The reoriented fabric is dipped through 1.45 sg PTFE two more times,dried and baked for 90 seconds at 300 F and 580 F respectively aftereach dip.

Example 16

Two layers of material made in example 4 are laid up so that the warpyarns of one ply run parallel to the warp yarns of the other and thefill yarns are at +30 in one ply and −30 in the other ply. A third layerconsisting of cast PTFE film with TiO2 as a UV block placed on one faceand the three layers (film and two fabrics) are laminated together usinga B. F. Perkins 100″, 100 Ton, 3 Roll Calendar the 4 fpm with 1750 psighydraulic pressure (≈2000 lbs/in.). The tacked laminate is then sinteredfor 120 seconds at 750 F.

The invention has been described with reference to various specific andillustrative and exemplary embodiments and techniques. However, itshould be understood that many variations and modifications may be madewhile remaining within the spirit and scope of the invention. Also,while individually coated plies made according to the above descriptionare particularly useful for forming antenna covers, industrial belts,structural materials, and expansion joints, the plies may also be usedto advantageously design multi-ply materials intended for other uses.Also, while reference has been made in the specification to amulti-layer material, in each case it is contemplated that themulti-layer material could be a multi-ply fabric where two or more ofthe layers are made of plies of fabric. The description in thisapplication is even more specifically believed to be useful formulti-layer materials that can be classified as multi-ply woven fabricswhere two or more of the plies are formed by a weaving process.

1. A flexible composite, comprising: a woven ply comprising anon-orthogonal orientation; a second woven ply; wherein the woven ply isindividually stabilized by a stabilizing agent; wherein the flexiblecomposite is configured to be a component of a a radome cover; and athird woven ply comprising an orthogonal orientation.
 2. A flexiblecomposite, comprising: a woven ply comprising a non-orthogonalorientation; a second woven ply: a third woven ply; wherein the wovenply is individually stabilized by a stabilizing agent; wherein theflexible composite is configured to be a component of a flexibleassembly and the flexible assembly is a radome cover; wherein the wovenply comprises a positive non-orthogonal orientation the second woven plycomprises a negative non-orthogonal orientation and the third woven plycomprises an orthogonal orientation.
 3. The flexible composite of claim2, wherein the stabilizing agent comprises a material selected from agroup consisting of a silicone rubber, a urethane rubber, a urethane, apolyurethane, a polyvinyl chloride, a polyvinylidene chloride, apolyvinyl alcohol, a fluoropolymer, and combinations thereof.
 4. Theflexible composite of claim 2, further comprising a protective film. 5.The flexible composite of claim 2, wherein the radome cover has atri-axial configuration.
 6. The flexible composite of claim 2, whereinthe radome cover comprises a trapezoidal tear strength of at least about300 pounds.
 7. The flexible composite of claim 2, wherein the radomecover is configured to have good RF performance at multiple frequencies.8. The flexible composite of claim 2, wherein the radome cover isconfigured to be air-supported.
 9. The flexible composite of claim 2,wherein the flexible assembly is a belt.
 10. The flexible composite ofclaim 9, wherein the belt further comprises flights extending from aface of the flexible composite.
 11. The flexible composite of claim 9,wherein the belt is an open weave belt.
 12. The flexible composite ofclaim 2, wherein the flexible assembly is an architectural fabric. 13.The flexible composite of claim 11, wherein the architectural fabriccomprises at least one of a flexible roof fabric comprising the flexiblecomposite and a skylight comprising the flexible composite.
 14. Theflexible composite of claim 2, wherein the flexible composite istranslucent.
 15. The flexible composite of claim 2, wherein the flexibleassembly is an expansion joint.
 16. The flexible composite of claim 2,further comprising a fluoropolymer film disposed on an interior face ofthe flexible composite.
 17. The flexible composite of claim 2, whereineach of the non-orthogonal orientations comprise a skew angle of about30 degrees to about 60 degrees.
 18. The flexible composite of claim 17,wherein the non-orthogonal orientation comprises a skew angle of up toabout 50 degrees.
 19. The flexible composite of claim 2, wherein theflexible composite is up to about 0.1 inches thick.
 20. The flexiblecomposite of claim 19, wherein the flexible composite is at least about0.04 inches thick.
 21. The flexible composite of claim 2, wherein theflexible composite has a weight of up to about 100 osy.
 22. The flexiblecomposite of claim 2, wherein the flexible composite comprisesstructural yarns at even increments.
 23. The flexible composite of claim2, wherein the multi-ply composite contributes to a loss of signal ofless than about 0.5 percent at multiple frequencies.
 24. An assemblycomprising: a flexible article including a woven ply, the woven plycomprising a positive non-orthogonal orientation; a second woven plycomprising a negative non-orthogonal orientation a third woven plycomprising an orthogonal orientation; and wherein the flexible articleis selected from a group consisting of a radome cover, a belt, anarchitectural fabric, and an expansion joint.
 25. The assembly of claim24, wherein the flexible article is a radome cover.
 26. The assembly ofclaim 25, wherein the radome cover has a tri-axial configuration. 27.The assembly of claim 25, wherein the radome cover comprises atrapezoidal tear strength of at least about 300 lbs.
 28. The assembly ofclaim 25, wherein the radome cover is configured to be air-supported.29. The assembly of claim 24, wherein the flexible article is a belt.30. The assembly of claim 29, further comprising a fourth woven plycomprising an orthogonal orientation.
 31. The assembly of claim 29,wherein the belt further comprises flights extending from a face of thebelt.
 32. The assembly of claim 24, wherein the flexible article is atleast one of an architectural roof fabric and a skylight.
 33. Theassembly of claim 24, wherein the flexible composite is translucent. 34.The assembly of claim 24, wherein the flexible article is an expansionjoint.
 35. The assembly of claim 34, further comprising a fluoropolymerfilm disposed on an interior face of the expansion joint.
 36. A radome,comprising: a first woven ply comprising a first non-orthogonalorientation, the first woven ply being individually stabilized by afirst stabilizing agent, the first stabilizing agent comprising an agentselected from a group consisting of silicone rubber, urethane rubber,urethane, polyurethane, polyvinyl chloride, polyvinylidene chloride,polyvinyl alcohol, and their copolymers with acrylic acid or acrylicacid esters or other vinyl ester monomers, fluoropolymers,fluoroelastomers, and combinations thereof; the first woven plycomprising yarns comprising fibers selected from a group consisting ofaramids, fiberglass, polyester, and combinations thereof; the firstnon-orthogonal orientation being a positive non-orthogonal orientationand having a skew angle of about 30 degrees to about 60 degrees; asecond woven ply comprising a second non-orthogonal orientation, thesecond woven ply being individually stabilized by a stabilizing agent;the second stabilizing agent comprising an agent selected from a groupconsisting of silicone rubber, urethane rubber, urethane, polyurethane,polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, andtheir copolymers with acrylic acid or acrylic acid esters or other vinylester monomers, fluoropolymers, fluoroelastomers, and combinationsthereof; the second woven ply comprising yarns comprising fibersselected from a group consisting of aramids, fiberglass, polyester, andcombinations thereof; the second non-orthogonal orientation being anegative non-orthogonal orientation and having a skew angle of about 30degrees to about 60 degrees; a third ply having an orthogonalorientation; wherein the radome is a flexible, air-supported radome;wherein the first woven ply and second woven ply are part of amulti-axial material, the multi-axial material having a thickness of upto about 0.3 inches; and wherein the radome contributes to a signal lossof no more than about 0.5% of a signal strength at least one frequencyused by radars.
 37. The radome cover of claim 36, wherein the flexibleradome cover has a trapezoidal tear strength of at least about 400pounds in at least three directions.
 38. The flexible radome cover ofclaim 36, further comprising a protective film.
 39. The radome cover ofclaim 36, wherein the flexible radome cover has a trapezoidal tearstrength of at least about 400 pounds in at least four directions. 40.The radome of claim 36, wherein the multiaxial material has structuralyarns at even intervals.
 41. The radome of claim 36, wherein, the firstnon-orthogonal orientation comprises a skew angle of about 40 degrees toabout 50 degrees; the second non-orthogonal orientation comprises a skewangle of about 40 degrees to about
 50. 42. The radome of claim 36,wherein, the first non-orthogonal orientation comprises a skew angle ofabout 60 degrees; and the second non-orthogonal orientation comprises askew angle of about 60 degrees.
 43. A radome, comprising: a first wovenply comprising a first non-orthogonal orientation, the first woven plybeing individually stabilized by a first-stabilizing agent, the firststabilizing agent comprising an agent selected from a group consistingof silicone rubber, urethane rubber, urethane, polyurethane, polyvinylchloride, polyvinylidene chloride, polyvinyl alcohol, and theircopolymers with acrylic acid or acrylic acid esters or other vinyl estermonomers, fluoropolymers, fluoroelastomers, and combinations thereof;the first woven ply comprising yarns comprising fibers selected from agroup consisting of aramids, fiberglass, polyester, and combinationsthereof; the first non-orthogonal orientation being a positivenon-orthogonal orientation and having a skew angle of about 60 degrees;a second woven ply comprising a second non-orthogonal orientation thesecond woven ply being individually stabilized by a stabilizing agent;the second stabilizing agent comprising an agent selected from a groupconsisting of silicone rubber, urethane rubber, urethane, polyurethane,polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, andtheir copolymers with acrylic acid or acrylic acid esters or other vinylester monomers, fluoropolymers, fluoroelastomers, and combinationsthereof; the second woven ply comprising yarns comprising fibersselected from a group consisting of aramids, fiberglass, polyester, andcombinations thereof; the second non-orthogonal orientation being anegative non-orthogonal orientation and having a skew angle of about 60degrees; a third ply having an orthogonal orientation; wherein theradome is a flexible, air-supported radome; wherein the first woven plyand second woven ply are part of a multi-axial material, the multi-axialmaterial having a thickness of up to about 0.3 inches; and wherein theradome contributes to a signal loss of no more than about 0.5% of asignal strength at least one frequency used by radars.